Coaxial connector and connection structure including the same

ABSTRACT

The present invention relates to a connection structure in which an inner conductor is combined with a detachable impedance compensator as well as a coaxial connector, an extendible pin and an impedance compensator used for the connection structure. Further, this invention relates to a microwave device connected both electrically and mechanically with the connection structure. An impedance compensation thereof means compensates electric discontinuities between the inner conductor and the extendible pin by mechanical arraying with a microwave device to be combined with the connection structure, whereby the protrusion formed at the impedance compensation means satisfies the conditions, b≦a/5 and c≦2b, when diameter of the impedance compensation means is a, thickness thereof is b, and size of the protrusion is c.

TECHNICAL FIELD

The present invention relates to a coaxial connector for high frequencytransmission line. More particularly, this invention relates to aconnection structure in which an inner conductor is combined with adetachable impedance compensator as well as a coaxial connector, anextendible pin and an impedance compensator used for the connectionstructure. Further, this invention relates to a microwave deviceconnected both electrically and mechanically with the connectionstructure.

In most areas of high frequencies and microwaves, a coaxial transmissionline consists of an inner conductor and an outer conductor. The innerconductor is made of a wire, while the outer conductor being normallymade of twisted metallic string bundles. The inner conductor and theouter conductor are electrically insulated by a dielectric material.

With recent increase in the use of coaxial line in wirelesscommunication fields, the frequencies of signals transmitted through acoaxial line has also been drastically increased to e.g., 18 GHz or 26.5GHz, and thus electric characteristics required for a coaxialtransmission line connector becomes more strict. In particular, wherefrequent insertions and separations of the connector are required e.g.,for testing a microwave element, it should be maintained that a rapidelectric connection while maintaining a low VSWR (Voltage Standing WaveRadio), superior electrically detaching characteristics, accurateimpedance matching, signal integrity, and the propagationcharacteristics.

BACKGROUND ART

Since a conventional coaxial connector comprises a thick innerconductor, it can hardly be installed on a small sized thin highfrequency plate, and its performance characteristics drop drastically ata frequency over 6 GHz. A connector structure 10, wherein size of theinner conductor has been reduced gradually to allow the inner conductorto fit to a high frequency substrate, and diameter of the dielectricmaterial has also been reduced to enable the impedance to be maintainedat 50Ω, is show in FIG. 1.

The conventional connector 10 in FIG. 1 comprises an outer conductor 12,first dielectric 14 and an inner conductor 16. The connector 10 iselectrically connected to a micro stripline (not shown in the drawing)of a microwave device 20 when it is installed within the microwavedevice 20. The inner conductor 16 of the connector 10 is electricallyconnected to an extendible pin 18. A second dielectric 30 made offluorine-resin (Teflon) and inserted into a hole 22 of the microwavedevice 20 and the extendible pin 70 inserted into a hole 32 formed inthe center of the second dielectric 30 are for impedance matching.

The inner conductor 16 of conventional connector 10 in FIG. 1 has adiameter reduced step-by-step toward the microwave device 20.Furthermore, size of dielectric 14 is also gradually changed to maintainan impedance of 50Ω. Thus, manufacturing of the dielectric 14 and of theinner conductor 16 becomes very troublesome; reflection property of thetransmitted microwave signals is worsen due to the reflection of themicrowave signals transmitted through the inner conductor, triggered bythe varying conductor size; and a drastic drop of the performancecharacteristics occurs when the connector is connected to a transmissionline. Actually, with the connector connected to a micro strip, asatisfactory performance cannot be expected at a frequency of 18 GHz orover. In addition, in the course of fixing the inner conductor by seconddielectric, the thin inner conductor can be disconnected by heat ofliquid form dielectric, and a correct line up of the extendible pin withthe dielectric is also very difficult.

FIG. 2 shows another coaxial connector with conventional structure.Since main body of the connector 50 is made in detachable manner, thisconnector 50 is advantageous in recycling purposes or in exchanges atsite. The connector 50 comprises an outer conductor 52, a dielectric 54,air 55, and an inner conductor 56. The connector 50 is connectedmechanically to a microwave device through a connection means, e.g. bolt57. An extendible pin 70 is inserted into the inner conductor 56 of theconnector 50. Here, an extendible pin 70 is inserted into a bead formdielectric 80 made of melted glass ceramic with high dielectric ratio inorder to compensate the difference in size of the extendible pin 70 fromthat of the inner conductor 56, and then, the dielectric 80 is insertedinto the hole 65 of the microwave device 60 to yield a tightly sealedstructure. In order to make a sealing construction, the hole 65 of themicrowave device 60 has a two stage structure, e.g. the hole 65 consistsof a first insertion stage with a diameter of 0.7 mm corresponding tothe thin diameter of the inner conductor 56 to maintain an impedance of50Ωand a second insertion stage corresponding to the diameter of theextendible pin 70. The extendible pin 70 is electrically connected tothe micro strip 62 of the microwave device 60 after it has passedthrough the second insertion stage.

However, in order to enable a connection with the conventional connectorin FIG. 2, a two stage drilling of the microwave device is required,which is not advantageous. Since diameters and depths of the insertionholes of a microwave device are very sensitive to the overallperformance characteristics of the connection structure, the insertionholes shall preferable be made as simple as possible. Moreover,manufacturing of the glass ceramic for the sealing structure istroublesome and requires a high cost.

DISCLOSURE OF THE INVENTION

The present invention, (conceived to solve the above problems,) aims toprovide a coaxial connector with superior electric characteristics,especially in high frequencies, and a connection structure including thesame.

Another objective of the present invention is to provide a coaxialconnector having a simple construction, an easy manufacturing process,as well as a low manufacturing cost, and a connection structureincluding the same.

Still another objective of the present invention is to provide a coaxialconnector showing superior characteristics in respect to insertion lossas well as reflection at an ultra high frequency on or over 15 GHz, anda connection structure including the same.

Finally, another objective of the present invention is to provide aconnection structure having a suitable construction for transmittingsignals externally from ultra high frequency module packages through amicro strip transmission line, as well as a coaxial connector, anextendible pin, an impedance compensator, and a microwave device usedfor this connection structure, to be connected with the impedancecompensator and the connection structure.

In order to achieve the above objectives, a connection structure inaccordance with the present invention, is for transmission of highfrequency signals, and comprises a connector body, which constitutes theouter appearance as well as housing of the connector; an inner conductorinstalled in the connector, including a first and a second terminalswhich are placed to face each other; a dielectric which insulates theconnector body from the inner conductor and determines impedance of theconnector; an extendible pin, which is connected electrically to thesecond terminal of the inner conductor; and an impedance compensationmeans having a hole for the extendible pin, whereby diameter of theinner conductor remains practically identical between the first and thesecond terminals, while diameter of the extendible pin is smaller thanthat of the inner conductor. The impedance compensation meanscompensates electric discontinuities between the inner conductor and theextendible pin by mechanical arraying with a microwave device to becombined with the connection structure, whereby the protrusion formed atthe impedance compensation means satisfies the conditions, b≦a/5 andc≦2b, when diameter of the impedance compensation means is a, thicknessthereof is b, and size of the protrusion is c.

In another embodiment of the connection structure as per the presentinvention, appropriate modifications of constructions of the coaxialconnector, the impedance compensation means, the extendible pin, and/orthe microwave device to be combined with the connection structure, aremade to achieve an impedance matching. For example, an impedancematching could be maintained by constructing the impedance compensationmeans as a circular dielectric made of Teflon with or without aprotrusion in the center of the dielectric. Alternatively, theextendible pin could be so constructed as to include a peak part and anextendible part, the latter having a larger diameter than that of theformer, and to create a space when the extendible pin is combined withthe circular groove of the inner conductor such that impedance of theconnection structure is controlled by the size of this space; or, aplurality of through holes are formed in the body of the impedancecompensation means to allow an impedance control by varying locationand/or size of these through holes. Further, an impedance matching canalso be achieved by appropriate modification of the construction of thedielectric ring or of the combination between the dielectric ring andthe substrate of the microwave device in a state a dielectric ring isinserted at a side of the extendible pin opposite to the side where theimpedance compensation means is combined.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a conventional connection structureincluding a coaxial connector as combined with a microwave device.

FIG. 2 is a cross-sectional view of another conventional connectionstructure including a coaxial connector as combined with a microwavedevice.

FIG. 3 is a perspective view showing a connection structure inaccordance with the present invention and a microwave device.

FIGS. 4 a through 4 d are cross-sectional views of a first embodiment ofa connection structure in accordance with the present invention.

FIGS. 5 a through 5 d are cross-sectional views of a second embodimentof a connection structure in accordance with the present invention.

FIG. 6 is a partial cross-sectional view of a third embodiment of aconnection structure in accordance with the present invention.

FIG. 7 is a partial cross-sectional view of a fourth embodiment of aconnection structure in accordance with the present invention.

FIGS. 8 a and 8 b are a front view and a perspective view, respectively,of the impedance compensator of a fifth embodiment of connectionstructure in accordance with the present invention.

FIGS. 9 a and 9 b are partial perspective views showing construction ofthe extendible pin of a sixth embodiment of a construction structure inaccordance with the present invention, and combination thereof with theinner conductor as well as with the impedance compensator.

FIG. 9 c is a partial perspective view showing construction of a variedextendible pin of the sixth embodiment of the construction structure inaccordance with the present invention, and combination thereof with theinner conductor as well as with the impedance compensator.

FIG. 10 a is a partial cross-sectional view of a microwave devicesuitable for combination with the above first as well as the secondembodiments of a connection structure in accordance with the presentinvention.

FIG. 10 b is a partial cross-sectional view of a microwave devicesuitable for combination with the above third as well as the fourthembodiments of a connection structure in accordance with the presentinvention.

FIG. 11 a is a partial cross-sectional view showing combination of aseventh embodiment of a connection structure as per the presentinvention with a microwave device.

FIGS. 11 b and 11 c are a cross-sectional view and a perspective view,respectively, of a dielectric ring used in the seventh embodiment of aconnection structure in accordance with the present invention.

FIG. 12 a is a partial cross-sectional view showing combination of aneighth embodiment of a connection structure as per the present inventionwith a microwave device.

FIGS. 12 b and 12 c are a cross-sectional view and a perspective view,respectively, of a dielectric ring used in the eighth embodiment of aconnection structure in accordance with the present invention.

FIG. 13 a is a cross-sectional view showing combination of a microwavedevice with connectors in accordance with the present invention, wheretwo connectors are connected by an extendible pin.

FIG. 13 b is a graph showing characteristics of a connection structurewhen combined as in FIG. 13 a.

FIG. 14 a is a cross-sectional view showing combination of a microwavedevice with connection structures in accordance with the presentinvention, where two connection structures are connected to a microstrip line of the microwave device.

FIG. 14 b is a graph showing characteristics of a connection structurewhen combined as in FIG. 14 a.

EMBODIMENTS OF THE INVENTION

Below, a detailed description of the embodiments of the presentinvention is given making reference to the accompanying drawings.

FIG. 3 is a perspective view showing a connection structure inaccordance with the present invention and a microwave device.

As shown in FIG. 3, a coaxial connector 100 comprises a body 110, adielectric 120, and an inner conductor 130. The connection structurecomprises a coaxial connector 100, an extendible pin 150, and animpedance compensator 160. The coaxial connector 100 as in FIG. 3 canbe, e.g. an SMA (Sub-Miniature Series A) 2.92 mm or 3.5 mm armconnector, whereby an SMA interface observes, for example, InternationalStandard MIL-C-39012, and is used in transmitting ultra high frequenciesof 18 GHz or 26.5 GHz to high frequency devices such as wirelesscommunication devices and test instruments. However, persons skilled inthe art to which the present invention belongs will easily understandthat the present invention is not limited to SMA type connectors, butallows all microwave connectors to be generally used therein. Forexample, the present invention can be applied to N series connectors,TNC connectors, BNC connectors, F series and G series connectors can beused in the present invention, in addition to DIN connectors, OSMPconnectors, SMB connectors, MCX connectors, SSMT connectors, OSMTconnectors, MMXC connectors. Furthermore, the present invention can alsobe applied to 0.141, 0.250, 0.0853, 0.144, RG316, RG188, ½″, and ⅞″right angled connectors, semi-rigid, or semi-flexible coaxial cables.

Body of the connector 110 can be made of stainless steel or othernon-ferrous metal, and can be plated by gold, white bronze, etc. Theconnector body 110 comprises combination holes 112, an inner conductorhole 114, and a combination means 116. The combination holes are forfixing the coaxial connector 100 with a microwave device 140, and theinner conductor hole 114 enables the inner conductor 130 to be exposedoutward, while the combination means 116 is for combination of thecoaxial connector 100 with a male connector (not shown in the drawing),whereby inner conductor 130 of the coaxial connector 100 is combinedwith inner conductor of a coaxial cable through the male connector.Although the combination means 116 is embodied in FIG. 3 as a screw, thepresent invention is not limit thereto, it can also take, e.g. a plugstructure.

The inner conductor 130 is surrounded by dielectric material 120, andthe body 110 formed at outer edges of the dielectric material 120 iselectrically connected to the outer conductor (not shown in the drawing)of the coaxial cable, whereby the outer conductor is usually used as aground plane, while the inner conductor 130 is used for transmission ofmicrowave signals. The inner conductor 130 is electrically connected tothe extendible pin 150. The extendible pin 150 inserted in an impedancecompensation means 160 to be combined with a connection structure, orthe dielectric material is inserted after inserting the the extendiblepin. The impedance compensation means 160 is made, e.g. of Teflon. Theimpedance compensation means 160 is for establishing impedance matchingbetween the coaxial connector 100 and the transmission line 147.

A variable defining characteristics of a signal frequency structure of acable, a connector, etc. is impedance, whereby a maximum energy can betransmitted when the impedances between two signal transmitting meansare the same, i.e. when an impedance matching is established betweenthem. However, when impedance changes are short in comparison to thewavelength, the signal loss by impedance mismatching can be ignored.Though the norm impedances of a coaxial cable are 50Ω, 75Ω, 93-125Ω,etc., a 50Ωcable is generally used as a compromise between a maximumpower transmission and a minimum line loss. On the other hand, incommunication and broadcasting industries, 75Ωcables are generally usedto minimize the line loss. As such, the impedance compensator 160 can beappropriately adjusted in different applications. If the impedancechanges in the course of signal transmission from the connector 100 tothe microwave device 140, a reflection loss is generated due to partialreflection of the wave entered into the microwave device 140, and if theimpedance is changed repeatedly, multiple reflections occur. Here, thetotal reflection coefficient equals to the vector sum of all reflectioncoefficients. These multiple reflections cause a resonance phenomenon.

The coaxial connector 100 is electrically connected to the transmissionline 147 of the microwave device 140 via the inner conductor 130 and theextendible pin 150.

The microwave device 140, being made of, e.g. aluminum or brass, isconnected through the coaxial connector 100 and the coaxial cable toanother electronic device, e.g. a Vector Network Analyzer (not shown inthe drawings) to exchange microwave signals. Although FIG. 3 shows amicrowave device 140 of quite simple construction for convenience ofexplanation, such microwave device 140 can be, for example, a coupler, amodulator, an amplifier or a spectrum analyzer. Body of the microwavedevice 140, comprises insertion holes 145 at both sides for insertion ofan extendible pin 150, in which holes 145, only the extendible pins 150are inserted, or together with an impedance compensator 160, as shown inFIGS. 4 through 9, an explanation of such cases is given below.

The microwave device 140 comprises combination holes 142 which pair withthe combination holes 112 of the connector 100 so that the connector 100is fixed to the microwave device 140 through these holes (112, 142). Theinsertion holes 145 at both sides of the body of the microwave device140 are formed to face each other in pairs, and a transmission line 147is placed on the strait line formed between by these pairs of insertionholes 145. The transmission line 147 is formed on a high frequencycircuit board, however, an illustration of the circuit board is omittedhere, to simplify the drawing. The transmission line 147 can be, e.g. amicro strip line, of which the width is determined by a function of thedielectric rate of the circuit board in use with the thickness thereof.That is, a relation expressed by w=f(ε, h) is valid when width of themicro strip line is w, dielectric rate of the circuit board is ε, andthickness of the circuit board is h.

In other embodiments of a connection structure according to the presentinvention, inner conductor 130 of a coaxial connector 100, dielectricmaterial 120, impedance compensator 160, insertion holes 145 of amicrowave device 140, are formed to have various constructions, adescription thereof follows below making reference to the accompanyingdrawings.

First Embodiment

FIGS. 4 a through 4 d are cross-sectional views of a first embodiment ofa connection structure in accordance with the present invention.

The coaxial connector 100 a in FIG. 4 a comprises a body 110 and aninner conductor 130. FIGS. 4 b and 4 c illustrates a cross-sectionalview and a front view, respectively, of the impedance compensator 160 a,while FIG. 4 d shows a cross-section view of the extendible pin 150. Aconnection structure as per the present invention comprises a connector100 a, an extendible pin 150, and an impedance compensator 160 a.

Referring to FIG. 4 a, the body 110 of the coaxial connector 100 ashapes the overall outer appearance of the connector 100 a, includes acombination means 116 for connection with a male connector (not shown inthe drawing), and is connected to an outer conductor of the coaxialcable, i.e. to a ground. Dielectric material 120 within the body 110surrounds the inner conductor 130, and has the same size in general. Itis possible to form a part of the dielectric material 120 by air gap.

The inner conductor 130 comprises a first terminal 132 to beelectrically connected to an inner conductor of a male connector, and asecond terminal 134 to be electrically connected to an extendible pin150. The grooves formed in the first and the second terminals 132, 134are for reducing electric resistance (at the contacting parts) byimproving the electric contacts. The inner conductor 130 maintainspractically the same diameter between the first and the second terminals132, 134, without any significant change, whereby diameter of the innerconductor 130 is much bigger than that of the extendible pin 150.

In the first embodiment of the present invention, the ending part 135 aof the second terminal 134 of the inner conductor 130 is formed deeperthan the terminal surface 115 of the connector body 110, i.e. the innerconductor 130 is constructed not to protrude outward over the connectorbody 110. Further, in the first embodiment of the present invention, theimpedance compensator 160 a comprises a protrusion 162 in the center asshown in FIG. 4 b, and a hole 164 is formed in the central protrusion asshown in FIG. 4 c, into which hole 164 an extendible pin 150 isinserted. The impedance compensator 160 a is inserted into the hole 117of the body 110 in a manner that the surface of the impedancecompensator 160 a with protrusion 164 fits to the terminal surface 115of the connector body. Accordingly, in a connection structure, whereinthe impedance compensator 160 is combined with the connector body, theprotrusion part 162 of the impedance compensator 160 a and only a partof the extendible pin 150 inserted in the hole 164 protrude outward overthe terminal surface 115. A connection structure as per the firstembodiment of the present invention, is combined with a microwave device140 as shown in FIG. 3 in a manner that the protrusion 162 is fittedinto the insertion hole 145, so that the protrusion 162 could be used asa fitting key without requiring an additional means for correct arrayingwhen the extendible pin 150 is inserted into the insertion hole 145 ofthe microwave device 140.

Since the inner conductor 130 of the connector has a diameter largelydifferent from that of the extendible pin 150 as described above, theimpedance difference between these two are big. The impedancecompensator 160 a compensates this electric discontinuity throughinstrumental arraying and achieves an impedance matching. Here, theinstrumental arraying means an instrumental arraying between theconnection structure and a microwave device with which this connectionstructure is combined.

A variable defining characteristics of a signal frequency structure of acable, a connector, etc. is called characteristics impedance ZO. Thecharacteristics impedance of a no loss cable, being related to the perlength inductance L and per length capacitance C, can be expressed bythe following Formula 1.ZO={square root}{square root over ( )} (L/C)[Ω]  [Formula 1]:

Characteristics impedance of a coaxial cable can be expressed by thefollowing Formula 2.Z0=138/{square root}ε Log 10(D/d)[Ω]  [Formula 2]:

Here, “D” stands for inner diameter of the outer conductor, while “d”stands for the outer diameter of the inner conductor.

A maximum energy can be transmitted when the impedances between the twosignal transmitting means are the same, i.e. when an impedance matchingis established between them. However, when impedance changes are shorterthan the wavelength, the signal loss by impedance mismatching can beignored. Though the norm impedances of a coaxial cable are 50Ω, 75Ω,93-125Ω, etc., a 50Ωcable is generally used as a compromise between amaximum power transmission and a minimum line loss. On the other hand,in communication and broadcasting industries, 75Ωcables are generallyused to minimize the line loss. The impedance can be increased bychanging diameter of the conductor, or by adding an air gap in thedielectric material

If the impedance changes in the course of signal transmission, part ofthe wave entered into the second medium is reflected. The reflectioncoefficient can be expressed by the following Formula 3.Reflection Coefficient=ρ=V _(i) /V _(R)=(Z _(R) −Z _(O))/(Z _(R) +Z_(O))   [Formula 3]:

Here, V_(i) and Z_(O) are input voltage and impedance, respectively, ofthe first medium, while V_(R) and Z_(R) are input voltage and impedance,respectively, of the second medium.

A reflection loss can be expressed by the following Formula 4.Reflection Loss [dB]=10 Log₁₀[1−(1−ρ²)]  [Formula 4]:

When a connection structure of the present invention is combined, forexample, with a microwave device 140 b as in FIG. 10 b, a reflectionloss (S11) of −20 dB, −15 dB, or lower can be obtained as shown in FIGS.13 b and 14 b, so that a power transmission rate of 95% or more can beachieved.

An impedance compensator 160 of a connection structure as per thepresent invention shall, as shown in FIG. 4 b, satisfy the conditions,

-   -   b≦a/5 and c≦2b,        when diameter of the impedance compensator 160 is a, thickness        thereof is b, and size of the protrusion is c. Where these        conditions are not met, an impedance matching is not achieved,        and desired reflection characteristics might not be obtained.

If not mentioned otherwise, these conditions apply also to the otherembodiments described below.

Second Embodiment

FIGS. 5 a through 5 d are cross-sectional views of a second embodimentof a connection structure in accordance with the present invention.

Those parts in the second embodiment identical with the correspondingparts in the first embodiment are indicated with same numerals and anexplanation thereof is omitted in the following descriptions. Theimpedance compensator 160 b in the second embodiment does not comprise aprotrusion, in contrast to the first embodiment. There exists amechanical difference in the connection structure depending on thetransmission line and the thickness of the substrate used in a microwavedevice. The existence and/or the length of the protrusion can beadjusted to fit the mechanical difference. When considering electricalcharacteristics, an impedance compensator 160 having no protrusion canbe constructed. According to an embodiment of the present invention, animpedance compensator 160 a with a protrusion can be used when diameterof the extendible pin is 0.2 mm˜0.4 mm; while an impedance compensator160 b without a protrusion can be used when diameter of the extendiblepin is over 0.4 mm.

Third Embodiment

FIG. 6 is a partial cross-sectional view of a third embodiment of aconnection structure in accordance with the present invention.

Those parts in the third embodiment identical with the correspondingparts in the above embodiments are indicated with same numerals and anexplanation thereof is omitted in the following description. In aconnector 100 b of the third embodiment, the inner conductor 130 a has asecond terminal 134 of which one end 135 b is on the same level with theterminal surface 115 of the body 110.

Fourth Embodiment

FIG. 7 is a partial cross-sectional view of a fourth embodiment of aconnection structure in accordance with the present invention.

Those parts in the fourth embodiment identical with the correspondingparts in the above embodiments are indicated with same numerals and anexplanation thereof is omitted in the following description. Innerconductor 130 b of the connector 100 c in the fourth embodiment has asecond terminal 134, of which one end 135 c protrudes over the level ofterminal surface 115 of the body 110 of the connector 100 b.

Fifth Embodiment

FIGS. 8 a and 8 b show the impedance compensator of the fifth embodimentof connection structure in accordance with the present invention.

The impedance compensator 160 c as per the fifth embodiment comprises abody 163 and a protrusion 162 rising from one side of the body 163.Although this embodiment is same as the above embodiments in that itcomprises a protrusion 162 and a hole 164 for insertion of an extendiblepin, it differs from the above embodiments in that the body 163comprises a plurality of through holes 165 a˜165 d formed therein.

These through holes 165 in the body 163 are formed at regions adjacentto the inner conductor where the most electric fields are gathered whenthe extendible pin is inserted in the extendible pin insertion hole 164in order to reduce the capacitance by reducing the effective dielectricrate of these regions. Thus, a capacitance adjustment is possible in thefifth embodiment through modifications of the size and the number of thethrough holes 165. The through holes 165 are placed preferably atregions between center of the extendible pin insertion hole 164 andlocations corresponding to R/2 when the radius of the impedancecompensator 160 c is R, whereby diameter of the through holes 164 can belarger than that of the extendible pin.

Sixth Embodiment

FIGS. 9 a and 9 b are partial perspective views showing construction ofthe extendible pin of the sixth embodiment of a construction structurein accordance with the present invention, and combination thereof withthe inner conductor as well as with the impedance compensator.

As shown in the drawing, the extendible pin 150 a in the sixthembodiment comprises a top part 152 and an extension part 154. Whilediameter of the top part is identical with that in the aboveembodiments, the extension part 154 has a diameter suitable forcombination with the circular groove 137formed at the second terminal134 of the inner conductor 130 d by insertion. As shown in FIG. 9 b, toppart 152 of the extendible pin 150 a is inserted in the extendible pininsertion hole 164 of the impedance compensator 160 a as in the aboveembodiments, while extension part 154 of the extendible pin 150 a isinserted in the circular groove 137, whereby the extension part 154proceeds preferably further into the inner conductor 130 d so as to forma space, ‘g’. Here, the space ‘g’ functions to reduce the electricfields flowing from the inner conductor 130 a to the earth. As such,capacitance of the connection structure can be adjusted by modifying thevolume of space ‘g’.

FIG. 9 c is a partial perspective view showing construction of a variedextendible pin of the sixth embodiment of the construction structure inaccordance with the present invention, and combination thereof with theinner conductor as well as with the impedance compensator. In thisvaried embodiment, extension part 154 of the extendible pin 150 a isinserted into the circular groove 137 of the inner conductor 130 dwithout forming the space ‘g’. Notwithstanding this, impedance of theconnection structure can be adjusted, for the impedance compensator 160a comprises a plurality of through holes 165 a˜165 d. The function andstructure of these through holes 165 a˜165 d are the same as thosedescribed in the above fifth embodiment.

Next, the modified structure of the microwave device 140 is describedwith reference to the extendible pin insertion hole 145.

As shown in FIG. 10 a, the extendible pin insertion hole 145 a of themicrowave device 140 a is formed with a predetermined inner diameter. Amicrowave device 140 a with this structure is suitable for combinationwith a connection structure according to the first or second embodimentof the present invention. Here, the inner diameter of the extendible pininsertion hole 145 a is, e.g. 0.7 mm.

In FIG. 10 b, the extendible pin insertion hole 145 b of the microwavedevice 140 b comprises a first insertion part 147 and a second insertionpart 149 having each a diameter different from one other, i.e. the hole145 b has a step structure. With a microwave device 140 b of thisstructure, a connection structure according to the third or fourthembodiment of the present invention can suitably be combined. In suchcase, diameter of the first insertion part 147 is practically the sameas the diameter ‘c’ of the protrusion 162 of the impedance compensator160.

Seventh Embodiment

FIG. 11 a is a partial cross-sectional view showing combination of aseventh embodiment of a connection structure as per the presentinvention with a microwave device, while FIGS. 11 b and 11 c are across-sectional view and a perspective view, respectively, of adielectric ring used in the seventh embodiment of a connection structurein accordance with the present invention. The seventh embodiment aims toimprove combination impedance matching when the extendible pin 150 ofthe connection structure is connected to the transmission line 147 ofthe microwave device 140.

As shown in FIG. 11 a, the microwave device 140 comprises an extendiblepin insertion hole 145 c formed in the body wall 146, a substrate 200,and a micro strip transmission line 147 formed on the substrate 200. Asinner diameter of the insertion hole 145 c is bigger than diameter ofthe extendible pin 150, the extendible pin 150 is surrounded by air ε0.Where the extendible pin 150 passes through the insertion hole 145 c andenters into the transmission line 147, a dielectric ring 300 is providedfor.

The dielectric ring 300 is formed in a ring shape with an extendible pininsertion hole 302 formed in the center thereof. The dielectric ring300, being made of, e.g. Teflon, functions to compensate thecapacitance, and thus, contributes to match an impedance between theextendible pin 150 and the transmission line 147. In addition, theextendible pin 150 preferably passes through the correct center of theinsertion hole 145 c, and the dielectric ring 300 enables not only theself-alignment of the extendible pin 150 but also compensates processingerror of the substrate 200 and the body wall 146.

If an arraying of the transmission line 147 with the extendible pin 150is required due to thickness of the substrate 200 in the seventhembodiment, the substrate is processed by ‘bb’, corresponding to theinsertion space, to yield a stepped structure. Here, the substrate 200is placed apart from the dielectric ring by a certain distance, ‘aa’,due to a processing error created by failure of the substrate 200 tocorrectly fit the body wall 146. Accordingly, there exists a spacebetween the body wall 146 and the substrate 200, which is expressedelectrically in L characteristic. The L characteristic can becompensated by capacitance compensation of the dielectric ring 300. Inother words, the dielectric ring 300 functions to compensate theprocessing error.

Eighth Embodiment

FIG. 12 a is a partial cross-sectional view showing combination of aneighth embodiment of a connection structure as per the present inventionwith a microwave device, while FIGS. 12 b and 12 c are a cross-sectionalview and a perspective view, respectively, of a dielectric ring used inthe eighth embodiment of a connection structure in accordance with thepresent invention.

In the eighth embodiment, arraying of the extendible pin as well asachieving of impedance matching are made using dielectric ring as in theabove seventh embodiment. Since the substrate 210 used in the eighthembodiment is thin and the extendible pin 150 can be arrayed on the samesurface with the transmission line 147 as shown in FIG. 12 a, noadditional processing is required to be made on the insertion part ofthe substrate. The dielectric ring 310 used in the eighth embodimentcomprises a ring part 314 and a tetragonal support part 316. Althoughthe tetragonal support part 316 is formed monolithic with the ring part314, it is formed backward from the ring part by the concave part 318,whereby the extendible pin through hole 312 is place at the center ofthe ring part 314 as shown in FIG. 12 c.

Referring to FIG. 12 a, the ring part 314 is combined with the concavepart 318 through insertion into the extendible pin insertion hole 145 c,while the tetragonal support part 316 contacts edge of the body wall 146of the microwave device 140 and is not inserted into the extendible pininsertion hole 145 c. The part of the ring part not inserted in theextendible pin insertion hole 145 c contacts the substrate 210.Accordingly, in the eighth embodiment, there exists no space between thesubstrate 210 and the body wall 146 of the microwave device 140, to beclosed by the dielectric ring 310, in contrast to the seventhembodiment. Thus, the dielectric ring 310 compensates capacitance as inthe seventh embodiment, and contributes to achieve an impedance matchingbetween the extendible pin 150 and the transmission line 147.Furthermore, the dielectric ring 310 functions in arraying theextendible pin 150 as well as in compensating the processing errors.

Inventors of the present invention have conducted experiments to provethe insertion and reflection characteristics of a coaxial connector anda connection structure including the same in accordance with the presentinvention, the results of which are shown in FIGS. 13 a through 14 b.

FIG. 13 a is a cross-sectional view showing combination of a microwavedevice with connectors in accordance with the present invention, whereintwo such connectors are connected by an extendible pin. FIG. 13 b is agraph showing characteristics of a connection structure combined as inFIG. 13 a.

In the above drawings, the microwave device 140 is an aluminum testfixture having 0.2 inch width. Two coaxial connectors 100 are connectedthrough an extendible pin 150 with 0.012 inch diameter made of brass. Asshown in FIG. 13 b, the electricity transmission rate was as high as99%, since the reflection loss (S11) was maintained lower than ca. −22dB until the frequency reached 20 GHz. The insertion loss (S21) showedfavorable characteristics maintaining −0.15 dB.

FIG. 14 a is a cross-sectional view showing combination of a microwavedevice with connection structures in accordance with the presentinvention, wherein two such connection structures are connected to amicro strip line of the microwave device, while FIG. 14 b is a graphshowing characteristics of a connection structure combined as in FIG. 14a. It can be seen from FIG. 14 b that the general characteristics wereslightly worsen when two coaxial connectors 100 were connected togetherthrough an extendible pin 150 and a transmission line 147, due to theperiodic characteristics by length resonance generated in thecharacteristics graph by the long transmission line 147. However, thepresent invention has provided even in such case a satisfactory resultwith an electricity transmission rate of 97%, since the reflection loss(S11) was maintained lower than ca. −15 dB until the frequency reached20 GHz.

Although the present invention has been described above with referenceto the preferred embodiments and the accompanying drawings, the scope ofrights of the present invention is not limited thereto, but rather,shall be determined by the claims attached herein after and theirequivalents, allowing various modifications and adaptations withoutdeparting the spirit of the present invention, as those skilled in theart to which the present invention belongs will understand.

INDUSTRIAL APPLICABILITY

The present invention provides a coaxial connector with superiorfrequency characteristics and a connection structure including the same,both of which have simple constructions, can easily be manufactured, andshow superior characteristics in respect to insertion loss as well asreflection at ultra high frequencies at or over 15 GHz. Furthermore, thepresent invention, by providing a connection structure having a suitableconstruction for transmitting signals externally from ultra highfrequency module packages through a micro strip transmission line, andby adopting detachable connector bodies, dielectric material as well asconnection pins, allows reuse of the connector bodies and the dielectricmaterial.

Moreover, since an impedance matching can be achieved by compensatingelectric discontinuities through mechanical arraying and a capacitancecontrol can be made by dielectric ring, etc. in the present invention,the present invention can largely enhance the interchangeability as wellas adaptability between various forms of connectors and microwavedevices.

1. A connection structure for transmission of high frequency signals,comprising a connector body, which constitutes the outer appearance aswell as housing of the connector; an inner conductor installed in saidconnector, including a first and a second terminals which are placed toface each other; a dielectric which insulates said connector body fromsaid inner conductor and determines impedance of said connector; anextendible pin, which is connected electrically to said second terminalof said inner conductor; and an impedance compensation means having ahole for said extendible pin, wherein diameter of said inner conductorremains practically identical between said first and said secondterminals, while diameter of said extendible pin is smaller than that ofsaid inner conductor.
 2. The connection structure as set forth in claim1, wherein said impedance compensation means compensates electricdiscontinuities between said inner conductor and said extendible pin bymechanical arraying with a microwave device to be combined with saidconnection structure.
 3. The connection structure as set forth in claim1, wherein said impedance compensation means includes a protrusion partformed in the center thereof to protrude toward a location where saidextendible pin is connected.
 4. The connection structure as set forth inclaim 3, wherein said protrusion formed at said impedance compensationmeans satisfies the conditions, b≦a/5 and c≦2b, when diameter of saidimpedance compensation means is a, thickness thereof is b, and size ofsaid protrusion is c.
 5. The connection structure as set forth in claim3, wherein a plurality of through holes are formed in the body of saidimpedance compensation means.
 6. The connection structure as set forthin claim 3, wherein said impedance compensator is combined with saidconnector body in a manner that the surface of said impedancecompensation means with said protrusion fits to the terminal surface ofsaid connector body.
 7. The connection structure as set forth in claim1, wherein said connector body comprises a terminal surface, wherebysaid second terminal is formed deeper than said terminal surface.
 8. Theconnection structure as set forth in claim 1, wherein said connectorbody comprises a terminal surface, whereby said second terminal isformed on the same level as said terminal surface.
 9. The connectionstructure as set forth in claim 1, wherein said connector body comprisesa terminal surface, whereby said second terminal is formed to protrudeoutward from said connector body.
 10. The connection structure as setforth in claim 1, wherein said extendible pin includes a peak part andan extendible part, the latter having a larger diameter than that of theformer, whereby said extendible part has a diameter suitable to fit intoa circular groove formed in said inner conductor of said connector. 11.The connection structure as set forth in claim 10, wherein saidextendible pin creates a space when it is combined with said circulargroove of said inner conductor, whereby size of said space isadjustable.
 12. The connection structure as set forth in claim 1,wherein a dielectric ring is combined at a side of said extendible pinopposite to the side where said impedance compensation means iscombined.
 13. The connection structure as set forth in claim 1, whereinsaid impedance compensation means is made of Teflon.
 14. The connectionstructure as set forth in claim 5, wherein said plural through holes areplaced at regions between center of said extendible pin insertion holeand locations corresponding to R/2 when the radius of said impedancecompensator is R.
 15. The connection structure as set forth in claim 14,wherein diameter of said through holes are larger than that of saidextendible pin.
 16. The connection structure as set forth in claim 1,wherein said connection structure is combined with a microwave device,and said microwave device comprises an extendible pin insertion holeformed in a step structure including a first insertion part and a secondinsertion part, having each a diameter different from one other, wherebydiameter of said first insertion hole is larger than that of said secondinsertion hole; while diameter of said extendible pin of said connectionstructure is practically the same as that of said second insertion holeof said microwave device.
 17. A coaxial connector used for a connectionstructure in accordance with claim
 1. 18. The coaxial connector as setforth in claim 17, wherein said coaxial connector is any one of SMAconnector, N series connector, TNC connector, BNC connectors, F seriesand G series connector, DIN connector, OSMP connector, SMB connector,MCX connector, SSMT connector, OSMT connector, MMXC connector, 0.141,0.250, 0.08563, 0.14, RG316, RG188, ½″, and ⅞″right angled connector,semi rigid, or semi flexible coaxial cables.
 19. The connectionstructure as set forth in claim 3, wherein said connection structure iscombined with a microwave device, and said microwave device comprises anextendible pin insertion hole formed in a step structure including afirst insertion part and a second insertion part, having each a diameterdifferent from one other, whereby diameter of said first insertion holeis larger than that of said second insertion hole; while diameter ofsaid extendible pin of said connection structure is practically the sameas that of said second insertion hole of said microwave device.